Timepiece movements, particularly mechanical movements, generally include cannon-pinions for driving display hands or discs. A first cannon-pinion is positioned and indented on the pivot-shank of the centre pinion.
The indenting operation consists in squeezing a tube comprised in the cannon-pinion opposite to a shoulder or to a recess of the pivot-shank. This squeezing is a manual operation, and the result thereof depends on the dexterity and sensitivity of the watchmaker, and is consequently random, which is annoying, since the object of indenting is to ensure a certain level of friction between the pivot-shank and the cannon-pinion during normal operation of the watch, while the manual time-setting operations performed by the user apply a higher torque than the friction torque; and therefore said friction torque should not be too high. Further, a friction torque that is too low will tend to cause interference' in the display state when accidental shocks are applied to the product.
Adjusting friction torque correctly is thus a difficult operation. Moreover, indenting frequently causes after-sales problems, since the cannon-pinion is a fragile component, and repeating indenting after disassembly often results in deterioration requiring the cannon-pinion to be replaced.
It is therefore important to control precisely the clamping force, and conventional manual indenting cannot achieve such precision or the required reproducibility.